The function
fread();
reads
nmemb
objects, each
size
bytes long, from the stream pointed to by
stream,
storing them at the location given by
ptr.
The function
fwrite();
writes
nmemb
objects, each
size
bytes long, to the stream pointed to by
stream,
obtaining them from the location given by
ptr.
RETURN VALUES
The functions
fread();
and
fwrite();
advance the file position indicator for the stream
by the number of bytes read or written.
They return the number of objects read or written.
If
size
or
nmemb
is 0,
fread();
and
fwrite();
return 0 with no change made to the
stream.
If an error occurs, or the end-of-file is reached,
the return value is a short object count (or zero).
The function
fread();
does not distinguish between end-of-file and error, and callers
must use
feof(3)
and
ferror(3)
to determine which occurred.
The function
fwrite();
returns a value less than
nmemb
only if a write error has occurred.